There are now only two things that can happen: Couples can start getting married again in California or the landmark case goes to the US Supreme Court.

Proponents of California's Proposition 8 had petitioned the court in February to review the ruling of a three-judge panel of the 9th Circuit which had found that Proposition 8 violates the Equal Protection Clause of the Fourteenth Amendment to the United States Constitution.

The judges wrote then that Prop. 8 'serves no purpose, and has no effect, other than to lessen the status and human dignity of gays and lesbians in California, and to officially reclassify their relationships and families as inferior to those of opposite-sex couples.'

Prop. 8 proponents have 90 days to file an appeal to the US Supreme Court.

The American Foundation for Equal Rights (AFER), the group which brought forth the lawsuit that led to the court case, said Tuesday's decision not to rehear 'marks a monumental turning point in our case for equality.'

'Today’s order is yet another federal court victory for loving, committed gay and lesbian couples in California and around the nation,' AFER co-founder Chad Griffin said. 'The final chapter of the Proposition 8 case has now begun. Should the United States Supreme Court decide to review the Ninth Circuit’s decision in our case, I am confident that the Justices will stand on the side of fairness and equality.'

The lawsuit challenging Prop. 8 was filed on behalf of two California couples who want to marry: Kris Perry and Sandy Stier and Paul Katami and Jeff Zarrillo.

The lead co-counsel for the plaintiffs, David Boies and Theodore B. Olson, held a telephone press conference after Tuesday's court decision was announced.

'Today’s decision affirms what we have said from the beginning: marriage is a fundamental right and the unjustifiable denial of that right seriously harms gay and lesbian couples and their families,' Boies said.

Added Olson: 'Today is a monumental day for the values that we all cherish as Americans: liberty, equality, dignity, and respect. Our Constitution not only protects these principles, it is what our fellow citizens expect from their government. This is a complete victory toward eliminating this last vestige of state-sponsored discrimination and second-class citizenship.'